System and method for supporting quality of service in vertical handovers between heterogeneous networks

ABSTRACT

A method, system, and business model are disclosed for supporting handover between a mobile host and a corresponding node located in a heterogeneous network. Handover paths are established to accommodate a plurality of quality of service properties. Admission control is performed that considers the established handover paths and an established first reservation path. Gateways are contacted to determine a handover path to use. The determined handover path is used to support vertical handover. A second reservation path is established while maintaining the first reservation path and the handover path.

FIELD OF THE INVENTION

[0001] The present invention relates generally to telecommunicationsystems and more particularly to supporting quality of service withvertical handoffs in wireless mobile telecommunication systems.

BACKGROUND

[0002] Recent years have witnessed an explosive growth of mobilecomputing and the emergence of new wireless technologies. The desire tobe connected any time, any where and in any way, leads to an increasingarray of heterogeneous systems, application, devices and operators. Suchheterogeneity is not likely to disappear in the foreseeable futurebecause the variety of application requirements makes it difficult tofind an optimal and universal solution. Likewise, an eagerness tocapture the market encourages competing organizations to releasenon-interoperable systems. As a result, the ability to provide seamlesstelecommunication services in such a heterogeneous environment may beimportant to the success of the next generation of mobile communicationsystems.

[0003] Mobile IP is a current standard for supporting mobility in IPnetworks. Mobile IP defines a home agent and a foreign agent. Thepackets destined for a mobile host are intercepted by the home agent andtunneled to the foreign agent. The foreign agent de-capsulates thepackets and forwards them directly to the mobile host. Mobile IP mayprovide a framework for allowing users to roam outside the home networkswithout disruption to their applications. However, known Mobile IPprotocol networks are built with the wired Internet in mind where theend host's mobility is limited and infrequent. Furthermore, the MobileIP protocol does not utilize network topology information and producesglobal updates whenever local mobility occurs, e.g., mobility betweenadjacent base stations in the same administration domain. Likewise,Mobile IP has no support for quality of service (QOS) features, such ashigh bandwidth requirements, high reliability requirements, and thelike.

[0004] Mobile IP does not support QOS because it treats different formsof mobility uniformly, and produces a new care-of-address for everyhandover from one base station to another. Therefore, a user moving ashort distance, e.g., between two adjacent base stations in the sameadministration domain, can experience significant disruption, e.g., lossand/or delay of signal, due to the frequent registration to the remotehome agent. Likewise, creating a new care-of-addresses for everyhandover introduces complexity and delay for a new QOS reservation orpath setup.

[0005] Known solutions include Cellular IP, Hawaii and othermicro-mobility related protocols. Such protocols attempt to limit theglobal updates because of local movement by either introducinghierarchical foreign agents or smart foreign agents depending on thenetwork topology. But the known schemes are based on homogeneousnetworks and the same administration domains. In other words, the knownschemes attempt to solve the horizontal handover problems but do notaddress vertical handover, e.g., handovers between base stations underdifferent administration domains. When vertical handover occurs, knownschemes no longer work because no common agent exists above two separateadministration domains. When vertical handover occurs, the mobile agentneeds to rely on the Mobile IP to resolve macro-mobility issues. Toenable seamless service, QOS capabilities should be provided duringvertical handover.

[0006] RSVP is the current standard for supporting Inte-Serv in an IPnetwork. It is known that to provide guaranteed service, reservation oradmission control is needed at the edge router regardless of the QOSmechanism used in the core network. RSVP or its extension is a popularsignaling protocol used by a host to request specific QOS capabilitiesfrom the network for particular application data streams. RSVP is alsoused by routers to deliver QOS requests to all nodes along the path ofthe data streams and to establish and maintain a state to provide therequested services.

[0007] A second set of protocols includes MRSVP, RSVP-A and othermodifications to the RSVP signaling protocol. Because the RSVP protocolis designed without the consideration of mobility by itsreceiver-initiating algorithm, MRSVP and its relatives are proposed tosupport mobility. These protocols are based on proactively set upreservations, however, in base stations where the application is likelyto travel. Such proactive reservation could lead to bandwidth waste dueto the large amounts of control messages needed to refresh the RSVP softstates.

[0008] Micro-mobility protocols only deal with mobility issues and haveno intrinsic QOS support. This problem can be addressed to some extentby using a common agent and reusing the common network path before andafter handover. The previous reserved path could be reused and QOSreservation and update information could be limited to local network.But the lack of QOS support during the handover period still exists.When the terminal moves from one base station to other base stations,packets in the previous base station are either dropped or forwarded tothe new base station without QOS support. Micro-mobility protocolsattempt to decrease packet loss but other QOS parameters such asbandwidth and delay are not considered. Likewise, no differentiationexists between the treatments of different applications. Differentapplications have different QOS parameters in terms of bandwidth, delayand loss so they are divided into QOS classes and receive differentiatedservice based on their classes. But known handover schemes treatapplications the same which violates the philosophy of differentiationand may lead to unnecessary system overuse.

[0009] As discussed above, when vertical handover occurs, micro-mobilityand its related QOS improving extensions could not be used because ofthe lack of common agent and common network path. Schemes such as RSVP,MRSVP and RSVP-A which produce global updates and introduce longerhandover periods can be used. A problem occurs regarding how to provideQOS support during this handover period.

[0010] Moreover, the upper-layer adaptation ability could also be takeninto account when adopting network layer QOS support. Since adaptationability is a basic requirement for elements working in the mobiledomain, the application, middleware, and transport layer are equippedwith some degree of adaptation mechanisms to deal with the packet lossor delay. Without the consideration of the upper-layer's adaptationability, IP layer handover adaptation may unnecessarily duplicate themechanism or even deteriorate the upper-layer's performance.

[0011] To enable seamless communications, there is a need for a QOSsupport system to support vertical handovers caused by mobile terminals.

BRIEF SUMMARY

[0012] A system and method are disclosed to support vertical handoverbetween heterogeneous networks. To accommodate handover, an accessrouter contacts a gateway specializing in supporting QOS during thehandover. Paths with different QOS properties are configured among peerhandover gateways. Thereafter, the gateway determines the correspondingdestination handover gateway and chooses the path most suitable for thecurrent handover requirements of applications. If no such path isavailable or the path is congested because of too much handover traffic,the handover is handled in an alternate way, such as in a best-effortfashion.

[0013] The handover gateways and related configured handover paths canbe organized in different ways. One way is that each operator maintainstheir own gateway and sets up handover contracts with adjacentoperators. As the number of operators increase, the scheme may becomeharder to manage. In another way, a hyper operator builds a specializedhandover network and utilizes bi-lateral contracts with main operatorsto employ specialized gateways and handover paths. When handover occurs,the gateway in each domain contacts the hyper operator's overlay networkto accomplish the handover process.

BRIEF DESCRIPTION OF THE DRAWINGS

[0014]FIG. 1 is a block diagram illustrating an exemplary communicationssystem for implementing the quality of service support system.

[0015]FIG. 2 is a block diagram illustrating a network architecturesupporting QOS handover in which operators have contract with adjacentoperators and no intermediate hyper operator is present.

[0016]FIG. 3 is a flow chart describing a handover process.

[0017]FIG. 4 is a flowchart illustrating exemplary reservation,admission control and choice of handover path according to the qualityof service requirements of the application.

[0018]FIG. 5 is a block diagram illustrating a network architectureaccording to the quality of service support system including a hyperoperator overlay network.

DETAILED DESCRIPTION

[0019] A quality of service (QOS) support system and method aredescribed that address horizontal and vertical handovers, andparticularly addresses vertical handover among different administrativedomains, e.g., operators. Horizontal handovers include handovers betweenbase stations that are using the same type of wireless networkinterface. Vertical handovers can include handovers between basestations under different administration domains. Other verticalhandovers can be addressed such as handovers between different wirelessnetwork technologies, handovers between heterogeneous terminals, andhandovers between heterogeneous applications for the same task. Abusiness model of hyper operator can construct a specific handovernetwork together with related AAA mechanisms. The hyper operator canobtain contracts with related operators and perform the handover for therelated operators.

[0020]FIG. 1 is a block diagram of an exemplary communications system100 for implementing the QOS support system. The communication system100 includes a communication network 110. The communications network 110can include networks such as a cellular network, satellite networks,local area networks (LAN) and Bluetooth networks. The communicationssystem 100 may also include a mobile host 120 and an end device 130. Themobile host 120 may allow a user to access the end device 130. Typicalmobile hosts 120 include a laptop computer, a mobile phone, such as acellular phone, a personal digital assistant (PDA) or other mobiledevices used to interface with end device 130 via the communicationsnetwork 110. Typical end devices 130 include a desktop computer, alaptop computer, telephones, such as cellular phones, a PDA or otherdevices.

[0021]FIG. 2 is a block diagram illustrating a network architecture thatsupports QOS handover where network operators have contract withadjacent operators and no intermediate hyper operator is present. TheQOS support system 200 includes various administration domains, such asDomain one 202, Domain two 204 and a third domain, such as the Internet206. The Internet 206 includes MPLS paths which are pre-configured byrelated administration domains after neighborhood information iscollected. Administration domains 202, 204 and 206 contain informationregarding the neighboring administration domains so that defined MPLSpaths can be used. The QOS support system 200 allows a user of themobile host 120 to communicate with the end device such as correspondingnode (CN) 222.

[0022] The QOS support system 200 interacts with administration domainsand provides necessary monitoring, signaling and maintenance functionsto help guarantee QOS support during a vertical handover and new pathreservation period. Regarding FIG. 4, described below, the QOS supportsystem in FIG. 2 includes a distributed architecture without a hyperoperator overlay network.

[0023] Referring to FIG. 2, a handover gateway (HO-GW) 208 is introducedin the administration domains 202, 204 to administer traffic during thevertical handover. A Multiprotocol Label Switching (MPLS) protocol, orthe like, is used to arrange defined QOS paths between theadministration domains 202, 204. Different MPLS paths having differentQOS properties may be used to allow for the various treatment ofhandover traffic based on the application requirements.

[0024] Domain one 202, Domain two 204 and the Internet domain 206 alsoinclude other telecommunications components such as routers (R) 210 andantennas or access points (AP) 212. The Internet 206 routers includegateway (GW) routers 214 that connect to the foreign agent (FA) gateway(GW) routers 216 of Domain one 202 and Domain two 204. The routers alsoinclude access routers (AR) 218 that can be accessed by antennas oraccess points (AP) 212 and that can be accessed by other components suchas home agent 220. The corresponding node (CN) 222, e.g., thecommunication peer of mobile host, can access the Internet domain 206via other routers, such as an edge router (ER) 224.

[0025] Differentiated services (Diff-serv), a known QOS technology, MPLSand RSVP protocols, or other similar applications, can setup pathsbetween the routers. Because of the scalability and traffic engineeringability, MPLS techniques can be used in the Internet 206 to set up thehandover path with different QOS properties. Other techniques could alsobe used. By way of example, two MPLS paths M1 and M2 can be establishedbetween Domain one 202 and Domain two 204. Depending on theapplications' requirements, either M1 or M2 could be used. The MPLSsupports traffic engineering and tunneling and allows for communicationframeworks which are scalable and suitable to implement in the corenetwork. Traffic engineering is used to distribute the traffic todifferent paths according to current network traffic load. Tunneling isused to overlay the packets to a new destination by wrapping the packetin another packet.

[0026] Vertical handovers usually occur in an area where two networkshave common coverage, known as an overlay area 226. Vertical handoverscan occur when users actively choose an access network based on theuser's own needs and can also occur in accordance with contracts withthe service providers. The user's needs may include application QOSrequirements, such as cellular networks for telephony and wireless localarea networks (WLAN) for multimedia streaming. Other needs may includecost, security, and the like. Heterogeneous networks exist toaccommodate the different needs of the user.

[0027] Vertical handover also may occur due to the limitations on accessnetwork coverage. Users change access systems when at the edge of acoverage area of an access network. When the user is located in theoverlay area 226, the user can switch to another access network usingvertical handover. If the user is not located in the overlay area 226,the user could lose the connection. When disconnection occurs, thesession is either reset or software may attempt to compensate in otherways, such as using different coding schemes to recover the losses frompackets already received.

[0028] The Internet protocol (IP) is a common network layer to connectdifferent administration domains and the Internet 206. The Internet 206includes some QOS support such as MPLS. Macro-mobility which may not behandled by described framework due to a lack of handover paths betweenoperators, may be handled by standard Mobile-IP protocols. Theadministration domains include versions of the micro-mobility algorithmsuch as HAWAII, Cellular IP, and the like, to help guarantee the QOSduring horizontal handover and MPLS paths within the network.

[0029] The corresponding node (CN) 222 uses a mobile-IP communicationprotocol to communicate with the mobile host (MH) 120. The home agent(HA) 220 includes functions, such as via software, to support a multiplepath reservation. The reservation is accomplished by the home agent (HA)220 via the RSVP protocol. The Mobile IP protocol is used to route thepackets, but without QoS support, and protocols such as RSVP, Diff-Servor MPLS are used to set up the QoS support. Domain one 202 and Domaintwo 204 include handover gateways (HO-GW) to accommodate the verticalhandover QOS. QOS between the handover gateways (HO-GW) and accessrouters are accomplished by domain-specific QOS mechanisms. Access point(AP) 212 includes layer 2 QOS mechanisms also according to differentunderlying layer 2 technologies such as 802.1Q/D and Subnet BandwidthManager (SBM) for the LAN.

[0030] MPLS paths M1 and M2 with defined QOS properties accommodateend-to-end QOS handling during vertical handover. The handover gateways(HO-GW) 208 for Domain one 202 and Domain 2 204 establish the MPLS pathsM1 and M2. For the administration domains, handover gateways (HO-GW) 208can be organized in a hierarchical manner where multiple band-overgateways HO-GW in the administration layers of one domain can beinvolved in setting up the handover path depending on the networktopology and handover traffic patterns. The handover gateways (HO-GW)208 are responsible for handover traffics of the multiple access routers(AR) 218. For access routers (AR) 218 near the overlay area withnetworks of another administration domain, more vertical handovers canoccur via the handover gateway (HO-GW) 208. Without a centralizedoperator such as Hyper Operator described later, the handover gateways(HO-GW) 208 in each administration domain identifies adjacent handovergateways of other operators. By logging the mobility pattern of itsclient over a period of time and examining the client's next operatorafter handover, the adjacent handover gateway information can bederived. Once the adjacent handover gateways are identified, MPLS pathscan be established.

[0031]FIG. 3 is a flow chart describing a handover process. At block300, an information gathering process begins such that whenever avertical handover occurs, the access router (AR) 218 informs asupervising handover gateway (HO-GW) 208 of the destinationadministration domain, e.g., Domain one 202 or Domain two 204. A linklayer mobility management algorithm could supply the access router withthe destination administration domain information. At block 310, uponreceiving the information, the handover-gateway (HO-GW) 208 queries aneighborhood database to determine whether the database includes theadministration domain and MPLS paths have been established. At block340, if the administration domain is included and the MPLS has beenestablished, the vertical handover can occur. At block 350, otherwise,the information is added to the database according to an updatingalgorithm so that the initialization process of the new MPLS paths forthe next vertical handover could be served. Because each access routercan only overlay a limited number of networks, only several rounds maybe needed for the handover-gateway (HO-GW) 208 to complete the learningto have full functionalities.

[0032] Thus, the handover gateways (HO-GW) 208 can learn and updateneighborhood databases and establish MPLS paths (M1 and M2 are used onlyas an example, multiple paths could be established based on therequirements) having different QOS parameters to each neighboringnetwork. The handover gateway (HO-GW) 208 can also communicate withother handover gateways (HO-GW) in the same administration domain toaccommodate performance and scalability. The handover gateway (HO-GW)208 monitors and maintains the MPLS paths and reports related QOSparameters to the access routers (AR) 218 to achieve new admissioncontrol algorithms. The handover gateways (HO-GW) 208 can also handlesignaling and tunneling tasks to begin and end handover traffics.

[0033] Standard MPLS procedure can be used to setup the routers, forexample, to choose the correct QOS classes, application QOS requirement,such as real-time or not real time, and differentiated handover QOSrequirements. The handover QOS requirements may be influenced by theapplication QOS requirements. According to Internet protocol 2 (IP2),handover is classified as fast handovers, smooth handovers and seamlesshandovers. Other types of handovers include a high-bandwidth handover. Afast handover is a handover that can satisfy strict delay bounds, forexample, real-time services. A smooth handover is a handover that canminimize a loss of packets. And seamless handover is a handover withminimum perceptible interruption of the services.

[0034] MPLS allows for a fine granularity in terms of QOS parameters,thus multiple paths can be established to obtain finer control ofhandover qualities and obtain a good balance between performance, priceand complexities. Some of the QOS parameters influencing applicationsinclude delay, loss and bandwidth, which can be accommodated bycombinations of the fast handover, smooth handover, high-bandwidthhandover and seamless handover.

[0035] To support vertical handover, the access router (AR) 218determines what kind of service the application of the mobile host (MH)120 requires during the handover. The determination can be achieved indifferent ways. For example, the application could inform the accessrouter (AR) 218 of the information at application initialization basedon the application requirements and its adaptation ability above the IPlayer, for example, adaptation ability in the transport layer,application layer, or any other layer above IP layer. In addition, theaccess router (AR) 218 can derive the information by examining flow portfields. In an IP packet header, the port field is used to show whatupper layer protocol is used in this packet, i.e., application categoryinformation. Examination of the flow port fields allows for applicationtransparency, but can achieve less accurate information than if theinformation were determined from the application.

[0036] After the paths are set and the access router receives a verticalhandover service requirement, the paths can be used in several ways. Thepaths can be used to forward residue packets from a current access point(AP) 212, for example one that is located in Domain one 202, to a newaccess point (AP) 212, for example one that is located in Domain two204, after handover occurs. The paths can also be used to forward newpackets from the current access point (AP) 212 to the new access point(AP) 212 during the period of a new reservation between thecorresponding node (CN) 222 and the new access point (AP) 212. If a newreservation cannot be achieved quickly, the path can be used to forwardthe packets until a new reservation is achieved or the session isterminated.

[0037]FIG. 4 is a flowchart illustrating exemplary reservation andadmission control according to the QOS support system. The mobile host(MH) 120 can include an application that accomplishes the reservationand admission control. The reservation path could occur via the linksbetween mobile (MH) 120 and the home agent (HA) 220 and the linksbetween home agent (HA) 220 and corresponding node (CN) 222. Byexamining how the QOS is supported before and after a vertical handover,the application runs in different phases.

[0038] A first phase includes the time before the handover in which theapplication typically operates. QOS support in this phase is achievedthrough maintained RSVP paths established by traditional RSVP protocols.A second phase includes the period from the time when handover isdetected in original base station to the time when the new RSVP path isestablished to the new base station. During this time period, the RSVPpath of the first phase and the selected configured MPLS path operatetogether to guarantee QOS support to the application. A third phaseincludes the period when the reservation path of the first phase and theMPLS handover path are released, and only the newly established path isused for the traffic that follows. After the third phase, theapplication can enter the first phase and begins regular operationagain.

[0039] At block 400, RSVP messages are used to provide the access router(AR), also the admission control point, 218 with the application's QOSrequirements during the non-handover operation phase. The RSVP messagesincluding information such as desired QOS (RSPEC), trafficcharacteristics (TSPEC) and flow differentiation (FILTER_SPEC). At block410, the access router (AR) 218 is provided with application's QOSrequirements of the second phase, e.g. the requirements during thehandover. Because mobile computing software can vary, to help guaranteeservice, a service loss profile, vertical handover service requirements,and probability of seamless communication factors can include thefactors used to express the adaptive QOS requirements during thetranslation.

[0040] At block 420, a configured MPLS path is selected in accordancewith the specified handover QOS requirements. The access routers (AR)218 can be used to determine particular MPLS paths such as M1 or M2suitable for the application using the information factors describedabove. Current traffic loads on the MPLS paths M1 and M2 can also beconsidered. Monitoring and reporting functions of the handover gateway(HO-GW) 208 can report the traffic load.

[0041] At block 430, admission control is used to determine whether toaccept the application's reservation or not. The received handoverrequirements are used to help determine whether or not to accept thereservation. For example, an admission control algorithm could be usedthat includes the delay on the selected MPLS path in the calculation ofend-to-end delay bounds regardless of whether the path is used for avertical handover. Other, less conservative, algorithms could be used,such as algorithms based on stochastic models to produce more accuratesystem usage information. At block 440, if the reservation is notaccepted, the reservation is terminated and resubmitted later as needed.

[0042] At block 450, if the reservation is accepted, when verticalhandover occurs between the mobile host (MH) 120 and the correspondingnode (CN) 222, the vertical handover is supported through the configuredMPLS paths. The new RSVP reservation is carried on from correspondingnode (CN) 222 to the mobile host (MH) through the new paths to the newnetwork. During the process time (the handover time), the QOS support isguaranteed until a new reservation is completed.

[0043] The QOS support system uses the above-described path setupprocess and advanced admission control process to achieve QOS supportduring vertical handover. The mobile host (MH) 120 is located in anoverlay area 226 of Domain 1 and domain 2. A QOS support systemalgorithm is initiated by a domain, e.g., Domain 1. The applicationsends the required QOS parameter to the access router in domain 1. Theaccess router contacts its supervised handover-gateway (HO-GW) todetermine which MPLS path can accommodate the application. Afteradmission control succeeds, path 1 is set up between the mobile host andthe corresponding node (CN) 222. The reservation process runs on top ofthe Mobile IP, e.g., an IP-IP tunneling QOS support is used.

[0044] When the mobile host (MH) 120 switches to Domain 2, verticalhandover occurs. After the mobile host (MH) 120 passes theauthentication and authorization procedures in Domain 2, the Domain 2access router informs the handover gateway (HO-GW) 208 located in Domain2, which in turn contacts the handover gateway (HO-GW) 208 located indomain 1 to establish a tunnel between the access routers located inDomain 1 and Domain 2. The tunnel uses the selected MPLS paths so thatthe end-to-end QOS requirements are followed. The access router (AR) 218located in Domain 2 renegotiates the path between the mobile host (MH)120 and the corresponding node (CN) 222. During setup, new packetscontinue to be sent to the Domain 1 access router and then tunneled tothe Domain 2 access router (AR) 218.

[0045] When the setup of the new path is complete, if the admissioncontrol succeeded, a router, e.g., the last router accomplishing theadmission control can send a confirmation message, such as a RESVconfmessage, to the Domain 2 router to reserve the path. The router can alsosend a message to the Domain 1 router to disconnect the old path, e.g.,such as a RESVtear message. Upon receiving the RESVtear message, theDomain 1 access router completes the packets in the access router'sbuffer and informs the Domain 1 handover gateway (HO-GW).

[0046] If the admission control fails, the RESVtear information isreturned to the Domain 2 access router. The Domain 2 access router canthen handle the call in accordance with a defined policy or applicationrequirements. Domain 2 can continue to use the tunnel between the newaccess router and attempt to renegotiate the reservation, e.g., after atime delay, to try to gain admission control. The Domain 2 access routercan negotiate with the Domain 1 access router (AR) 218 about how longthe tunnel is maintained. The Domain 2 access router (AR) 218 can alsonegotiate with the mobile host about how the adaptation can occur.Because the connection is maintained, QOS support is used during thisprocess too.

[0047]FIG. 5 is a block diagram illustrating a network architectureaccording the QOS support system 500, where the architecture includes ahyper operator overlay network (HO-OL) 510. The hyper operator overlaynetwork (HO-OL) can exist in the Internet domain 206 which interactswith the related gateways in the administration domains, e.g., Domainone 202 and Domain two 204. The hyper operator overlay network (HO-OL)510 can reduce the number of tasks performed by the handover gateway(HO-GW) 208 in the administration domains. The hyper operator overlaynetwork (HO-OL) 510 can control several functions, such as, establishingthe MPLS paths, monitoring and maintaining the traffic in the MPLS pathsM1 and M2, and cooperating with the access router (AR) 218 to performthe admission control. The handover gateway (HO-GW) 208 would thenadminister local optimization, such as by providing QOS support in theadministration domain.

[0048] Because the hyper operator overlay network (HO-OL) 510 has globalknowledge of each administration domain, optimal vertical handoverperformance could be achieved. The hyper operator overlay network(HO-OL) 510 can interact with related routers located in the corenetwork to support QOS routing and accelerate the reservation process ofthe new path. The hyper operator overlay network (HO-OL) 510 can alsoaddress other related policy issues such as security and AAA(authentication, authorization, accounting), and the like, which aregenerally not easy for one operator. The hyper operator overlay network(HO-OL) 510 can also provide a signaling path so that the architectureis easy to implement.

[0049] Thus, QOS support systems are shown using a hyper operator overly(HO-OL) architecture or a distributed architecture. The architecturesinclude vertical handover gateways (HO-GW) 208 to support seamlessvertical handovers. The frameworks can support varying handoverrequirements in terms of delay, loss and bandwidth by choosing an MPLSpath. The frameworks can also account for the adaptation ability of theapplication layer by allowing the application to specify the QOSrequirements after considering the applications mechanisms. The networkcan then provide necessary adaptation ability and avoid duplicatefunctionalities. The frameworks support different applications.

[0050] While the invention has been described above by reference tovarious embodiments, it will be understood that many changes andmodifications can be made without departing from the scope of theinvention. It is therefore intended that the foregoing detaileddescription be understood as an illustration of the presently preferredembodiments of the invention, and not as a definition of the invention.It is only the following claims, including all equivalents, which areintended to define the scope of this invention.

We claim:
 1. A method for supporting handover between heterogeneousnetworks, comprising: establishing a first reservation path;establishing a handover path to accommodate a quality of serviceproperty; performing admission control that considers the establishedhandover paths and the first reservation path; contacting gateways todetermine a handover path to use during handover; using the determinedhandover path to support vertical handover; and establishing a secondreservation path while maintaining the first reservation path and thehandover path.
 2. The method of claim 1 wherein the handover pathcomprises MPLS paths.
 3. The method of claim 2 wherein the MPLS pathsaccommodate more than one quality of service property.
 4. The method ofclaim 1 wherein an access router contacts the gateway.
 5. The method ofclaim 4 wherein the access router informs the gateway of a destinationadministration domain.
 6. The method of claim 1 wherein the handovercomprises a vertical handover.
 7. The method of claim 1 wherein thedetermination comprises querying a database.
 8. The method of claim 1further including contacting gateways with a hyper operator.
 9. Themethod of claim 1 wherein at least one of the first and secondreservation paths comprise an RSVP path.
 10. A system for supportinghandover between a mobile host and a corresponding node in aheterogeneous network, comprising: a first reservation path to connectthe mobile host and the corresponding node; a handover path toaccommodate a quality of service property; an admission controlapplication that considers the established handover paths and the firstreservation path; a gateway to determine a handover path to use duringhandover, wherein the determined handover path is used to supportvertical handover; and a second reservation path to connect the mobilehost and the corresponding node, the second reservation path beingestablished while maintaining the first reservation path and thehandover path.
 11. The system of claim 10 wherein the handover pathcomprises MPLS paths.
 12. The system of claim 11 wherein the MPLS pathsaccommodate more than one quality of service property.
 13. The system ofclaim 10 further including an access router, wherein the access routercontacts the gateway to determine a handover path to use.
 14. The systemof claim 13 wherein the access router informs the gateway of adestination administration domain.
 15. The system of claim 10 whereinthe handover comprises a vertical handover.
 16. The system of claim 10further comprising a database, wherein the determined handover path isestablished by querying the database.
 17. The system of claim 10 furtherincluding a hyper operator wherein the hyper operator contacts thegateways.
 18. The system of claim 10 wherein at least one of the firstand second reservation paths comprise an RSVP path.